The U.S. top official overseeing the Gulf of Mexico oil spill response says bad weather will delay by two or three days the completion of the relief well designed to permanently seal the ruptured oil well.

Retired Coast Guard admiral Thad Allen told reporters Tuesday that while drilling will cease, crews will remain at the scene during the delay.

Oil company BP announced earlier Tuesday that a strengthening tropical weather system has forced it to suspend drilling.

Allen said he now expects the last segment of the relief well will be completed between Sunday and Tuesday of next week.

Pressure test

In the meantime, Allen said BP is considering a pressure test on the well to determine if hydrocarbons have leaked into the outer wall of the well pipe.

Last week, BP sealed the well from the top with mud and cement in a procedure known as a static kill. Allen said Tuesday the pressure test could help determine if the static kill sealed the well down to the oil reservoir.

But Allen said, regardless of the test, the intention is still to pump additional cement and mud into the main well once the relief well is completed.

Billions spent

BP said Monday it has spent $6 billion in response to the massive oil spill. It said those costs include claims paid to Gulf residents, relief well drilling, containment efforts, and the procedure that sealed the top of the well.

The company also said Monday it has made a $3 billion initial deposit into the $20 billion fund to pay claims for residents affected by the spill.

An April 20 explosion on a rig operated by BP killed 11 people and ruptured the well, sending millions of barrels of oil into the water and polluting the region's shoreline.

Oil remains

Allen said a lot of oil remains in the water and on the shoreline, and the government plans to continue to hold BP accountable for the ongoing clean up.

He has also said the government is beginning to study the long-term impact of the spill on the region's economy and environment. Many U.S. consumers are still reluctant to buy seafood from the Gulf, fearing that it may be contaminated.

A U.S. government study published last week found that about 75 percent of the oil that spilled into the Gulf has been collected, burned off or dissipated naturally.